Stolen from sxoc, but it makes me laugh, though I would share the love....
No it doesn't...
When you select reverse the following sequence happens..
1) The gearbox gear position nodicator flangulates the precise positional input whirlygig frequency to the barbar valve.
2) The barbar valve compresses this flangulation into a nurfelbyte of terra informational transport system (T.I.T.S.) standard oscillation
3) This engages the turbocharger brake.
4) The turbocharger brake is a long rod that lives in the primary section of the exhaust. On the turbo end of this rod is a small asbestos hamster
5) When engaged, the asbestos hamster hangs onto the turbine wheel with all his strength to stop the turbo spinning
*Note:
the asbestos hamsters on the 200sx are not particularly strong. If you hear a graunching noise when you select reverse, its not the gear synchro's meshing, its actually an asbestos hamster getting caught up in the spinning bits.
Don't worry though, Nissan addresses this problem by fitting a lifetime's supply of asbestos hamsters. The large box section of exhaust just before the rear axle contains over 5000 asbestos hamsters.
If you need to replace them, the Nissan part number is:
8088390-001
Alternatively, Nismo do an uprated hamster called 'Hyper-Rodent-R'
So now you know